Method of purifying iron scale



June 7, 1927.. 1,631,423

A. LUCAS METHOD OF PURIFYING IRON SCALE 7 Filed May 16, l925 INVENTOR/7/770/7 Z (/6451 BY ATTOR N EY Patented June 7, 1927.

UNITED s'TATEs' i 1 its 1,423-

ANTON LUCAS, or KANSAS cIrY, mssoun'r.

mrrnon or runrr mc moi: scans.

' Applicati olifiled n'ovember 1c, 1925. Serial no. 69,333.- j

My invention relates to a method of purifying iron scale as a step 111the manufacture of an aluminothermic mixture, of a characterparticularly adapted for use in,

5 welding car rails and making heavy repairs, as of iron or steel beams,girders or the like, the principal object of the invention being theseparation of sand, dirt or other foreign matter from the scale, toprovide a mechanically pure product and insure against variability inchemical reaction due to unbalanced oxide content in the mixture.

A mixture of the character described consists of calcined ferroso-ferricoxide and a powder of aluminum or other metal or alloy capable ofreducing the oxide. For convenience, only aluminum will be hereinaftermentioned as the reducing agent, with the understanding that othermetals or alloys capable of performing the reduction may be employed as.well, without departing from the invention.

may be secured from different sources, as

- from magnetic iron stone or otherore, the

what-large quantities, has been fed bacli tothe blast furnace as anaddition to the charge, but considered of inferior value,

partly because of its impurities, principally mechanical, due to thepresence with the scale of mill dust and frequently small -pieces ofiron. Scale of this kind before mixture with the aluminum elementis'calcined or roasted, preferably with an om'dizing flame to drive offany liquid content or chemical impurities, oxidize any particles of ironpresent with the scale, and make the oxygen content uniform. 7

When so treated the roasted product is screened, and. in some instancesattempt is made to separate the scale from its impuri ties by magnetictreatment. I- have found, however, that screening or sifting isineffectual, as any mesh coarse enough to pass the scale flakes orparticles will also pass solid impurities such as sand, brick or ironparticles of such size and in sufficient quantities to affect reactionin the reducing crucible. The scaleflake is quite brittle and may bepulverized in a crusher under a the .one yieldably and the otherfixedly, and

hopper 5 and cascaded from the rolls screen 7.

While oxide desirable for the macbiiief pressure which will not affectthe harder particles constituting the impurities, V I have, therefore,added toth e customary process of purifying the scale, a mechanical stepconsisting of crushing -the scale between relatively soft rollers,having suflicient tension to pulverize the scale, but yieldable to theharder particles, and then separating product by airblast or, finescreening or both. I

The accompanying drawing illustratesa' form of crusher which maybeemployed for the purpose, consisting of rubber or like rolls 1, onshafts 2, journalled in a frame 3,

driven by a belt l-to rotate the rollers in the opposite directions andfeed the mixture 7 therethrough as in an ordinary mangle. The materlalmay be fed t6 the rolls from a through an air blast, indicated by 6,onto a The loose roller is urged to contact with the fixed one bysprings 8, sufficiently strong to press and crush the scale, butyieldable-to allow the loose'roller .tospread upon the passage of anexcessively large solid particle I therethrough, the material of whichthe rolls are composed being sufliciently soft to 1 embed the usual runof hard material during the feeding travel. M

The drawing also illustrates thematerial and the methodof treatment, 9designating the material coming tothe crusher, compristies, 10 a pieceof brick,sand, iron or other 7 hard material'embedded in" the softrollers,

ingthe scale flakes and commingled impuri-' 11, light dirt and dustseparated fiom the heavier particles by the air blast, 12-the purepulverized iron scale which is passed through the fine screen tohecollected in a 4 storage-receptacle and 13 the heavier im-f purities"which have been rejected by the screen. p v

I have found that by so treating the iron scale I eliminate impurities.which, if 31- lowed to remain in the scale, would upon the reactionproduce gases that would remain in the solidified metal, causing blowholes and other defects, and a'nmch more effectivematerial may heproduced with which a surer and more effective weld may be made.Inasmuch as mixture of the purified scale with proper reducing agentsand the method of use of the mixture is well known, I

will not describe the same in detail, as neither the generic mixture,the welding process nor any specific apparatus for crushing the scale isclaimed as my invention, the

5 invention including only the method of treating the scaleforpurification.

What I claimjand desire to secure by Letters-Patent is 1. The method ofpurifying iron scale,

10 consisting of crushing the scale between crushing elements yieldableto s bstances of greater hardness than the sea e and then separating thelight crushed substances from the other substances, and then separatingthe scale from the remaining substances. 2. The 'method of purifyingiron scale,

consisting of passing mill scale between feeding rolls of a materialsufficiently resistant to crush the scale, but yieldable to substancesless brittle thanthescale, and then separating the light crushedsubstances from

